The Icelandic sagas are ancient tales of brave deeds and lives and loves, with a cast of thousands – but how true to life are they? Pádraig Mac Carron and Ralph Kenna analyse the interactions between the characters and find that social networks of the Viking era were very similar to those of today.

The Íslendinga sögur – or sagas of Icelanders – purport to describe events in the period following the settling of Iceland about a thousand years ago. The sagas tell of families and feuds, of warfare and warriors, of lives and loves, betrothals and betrayals. The antiquity of the texts and their unique narrative style make them an important element of world literature. Some consider the sagas to contain information on Viking life, while others object that such tales are entirely fictional, with no basis in reality. With overlapping plots in different texts involving thousands of characters and their interactions, their huge network of interactions makes them an ideal study for statistical analysis.

The approach follows a previous study of mythological and epic literature, which compared the Anglo-Saxon epic Beowulf, Homer’s Iliad and the Irish epic, Táin Bó Cuailnge [1]. One may ask questions about the bases for such tales and attempt to uncover what quantitative information may have been hidden for centuries within the pages of ancient manuscripts. For theÍslendinga sögur Mac Carron and Kenna gathered data for 18 narratives, five of which contain over 100 characters each. These are Njáls saga, Laxdæla saga, Vatnsdæla saga, Egils saga Skallagrímssonar and Gísla saga Súrssonar. They examined these individually in order to compare different sagas to each other. They also studied the sagas collectively – a network of 1549 characters – to gain insight into the structure of the overall saga society [2].

The networks underlying saga society have similar properties to real-world social networks; they are far more clustered than their random counterparts - Viking society is small world. Individuals in the society are connected to each other by an average path length of 5.5 – remarkably close to the six degrees of separation of modern society. A propensity to disfavour odd numbers of hostile links is related to the notion of structural balance – in the Viking era, the enemy of an enemy is a friend. Some of the family sagas are assortative, meaning that characters associate with other characters similar to themselves. The outlaw Gísla saga is by contrast disassortative. A strong overlap between the communities in Njáls saga and Laxdæla saga offers support to the theory that one saga may have been used as a source for the other.

Traditional studies of literature focus on individuals and events. This new statistical approach looks instead at the collections of interactions between characters. It offers a new and exciting way to make quantitative comparisons both between the sagas as well as to compare to other literary genres. The new approach opens new windows for us to peer into our dim and distant past.